Field of the Invention
The present invention relates generally to systems and methods for de-icing aircraft, and more particularly to a system and method for the forced air de-icing of aircraft with an adjustable forced de-icing system.
Description of the Related Art
De-icing of aircraft involves removing snow, ice, and/or frost from various surfaces of the aircraft. De-icing is traditionally performed by spraying dry or liquid chemicals on the aircraft. In some examples, a heated mixture of a de-icing agent, such as antifreeze (or glycol), and water is sprayed by pressurized air through a nozzle provided on a movable boom secured on a stationary or mobile platform. Examples of known de-icing systems and methods are described in U.S. Pat. Nos. 5,244,168, 5,755,404, and 6,250,588. These de-icing systems and methods use a fixed nozzle in fluid communication with a fixed supply of the de-icing agent and pressurized air. The de-icing agent and pressurized air are mixed in the nozzle and delivered from the nozzle as a jet of pressurized de-icing agent.
Conventional de-icing systems are configured for fixed nozzle operation. In other words, the nozzle has a fixed aperture (i.e., not adjustable) and the jet velocity is determined by air source or compressor/blower speed that delivers pressurized air at a fixed flow rate. The optimal jet velocity is attained when a compressor/blower used to deliver the air delivers a pressure ratio of about two, resulting in a jet velocity of about 1,000 ft/sec at the nozzle exit. Effectiveness of conventional forced air de-icing systems is primarily dependent on the velocity of the jet downstream of the nozzle exit. The higher the jet velocity, the more pressure and force is imparted to the aircraft surface to remove ice and snow. The jet velocity typically decays rapidly as the forced air stream mixes with the surrounding air. Some de-icing systems have the capability to reduce the power to the compressor/blower and hence nozzle exit velocity; however, such operation is still based on using a fixed nozzle with a diminished jet velocity at increased distance.
While conventional de-icing systems and methods are effective in removing snow, ice, and/or frost, they are associated with a number of disadvantages. Weather conditions during de-icing operations often change continuously such that a jet delivered from a fixed nozzle rarely performs in an optimum manner to maximize the de-icing efficiency while minimizing use of the de-icing agent. Also, overblow of snow from the aircraft reduces visibility around the aircraft, thereby creating a hazard for ground workers. Conventional de-icing systems require the operator to get close to the aircraft (typically five to ten feet) to maintain an effective snow and ice removal capability of the fixed nozzle which rapidly diminishes if the distance between the nozzle and the aircraft is increased. In addition, noise generated by conventional fixed nozzles is often close to or exceeds the permissible noise limit that is enforced at various airports.
It would be desirable to develop new systems and methods for de-icing aircraft that overcome the deficiencies associated with conventional de-icing systems and methods.